Voltage regulator circuits employing a reactor coupled with a movable contact to provide current in full cycle and half cycle position of its tap changer is disclosed within U.S. Pat. No. 2,342,084. A transformer tap changing system employing a first and second pair of stationary contacts in tandem connection is described within U.S. Pat. No. 3,015,057 issued to Alverson. The Alverson patent provides a transformer tap changing system in which the reactive load introduced by the bridging reactor is substantially the same for all positions of the associated tap changer. A voltage regulator providing a wide range of voltage regulation is described in U.S. Pat. No. 4,168,461 issued to Fehlmann et al. This patent provides a wide range of voltage regulation by employing at least two regulators connected with their exciting windings in parallel and their series windings in series. All of the aforementioned U.S. patents are incorporated herein for purposes of reference.
The instant invention improves over the regulation disclosed within Fehlmann et al by employing a single voltage regulator having a common exciting winding and a tandem arrangement of a first and second regulating winding to provide both a wide range in voltage regulation and a negligible impedance at the maximum voltage position.